Communication Apparatus and ID Packet Recognition Method Thereof

ABSTRACT

A communication apparatus is provided. The communication apparatus includes an RF module and a scan module coupled to the RF module. The RF module receives an RF signal and generates an intermediary signal corresponding to the RF signal. The scan module recognizes a time-domain pattern corresponding to the intermediary signal, and determines whether the RF signal comprises an ID packet according to the recognized time-domain pattern.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/324,340, filed on Apr. 15, 2010, the entirety of which isincorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is related to a communication apparatus, and moreparticularly to a communication apparatus for recognizing an ID packetcomprised in an RF signal.

2. Description of the Related Art

Bluetooth wireless technology is a short-range communicationstechnology, which is able to replace cables which connect portableand/or fixed devices for communications while maintaining high levels ofsecurity. The key features of Bluetooth technology are robustness, lowpower, and low cost. The Bluetooth specification defines a uniformstructure for a wide range of devices to connect and communicate witheach other.

All Bluetooth devices default to a standby mode. In a standby mode,unconnected devices periodically listen for messages. This procedure iscalled scanning which is divided into two types: page scan and inquiryscan. A page scan is defined as a connection sub-state in which a devicelistens for its own device access code (DAC) (via a “page”) for a scanwindow duration (11.25 ms) every 1.28 seconds in order to set up anactual connection between devices. An inquiry scan is very similar to apage scan except that in this sub-state the receiving device scans forthe inquiry access code (IAC) (via an “inquiry”). The inquiry scan isused to discover which devices are in a range and addresses and clocksof devices in the range. Therefore, a normal scan procedure is typicallyperformed during the scan window (11.25 ms) for a Bluetooth device.

A page sub-state is used by a master Bluetooth device to activate andconnect to a slave Bluetooth device which periodically wakes up in thepage scan sub-state. The master Bluetooth device tries to capture theslave Bluetooth device by repeatedly transmitting the slave's deviceaccess code (DAC) in different hop channels. In the page sub-state, themaster Bluetooth device transmits the device access code (ID packet)corresponding to the targeted slave Bluetooth device for connection,rapidly on a large number of different hop frequencies. Since the IDpacket is a very short packet, the hop rate can be increased from 1600hops/s to 3200 hops/s. Since the Bluetooth clocks of the master and theslave Bluetooth devices may not be synchronized, in this case, themaster Bluetooth device would not precisely know when the slaveBluetooth device has waken up and which hop frequency the slaveBluetooth device is on. Therefore, the master Bluetooth device transmitsa train of identical DACs at different hop frequencies, and listens inbetween the transmitted intervals until the master Bluetooth devicereceives a response from the slave Bluetooth device. FIG. 1 shows atiming diagram illustrating page and inquiry scan transmissions, whereinpairs of page or inquiry scan messages 100 are repeated within the scanwindow (11.25 ms) in accordance with the Bluetooth specification.

However, when in standby mode, a Bluetooth device will consume power dueto the inquiry scan and the page scan. This can be undesirable in thatconsiderable battery power is consumed even while the Bluetooth deviceis unconnected.

Therefore, a communication apparatus and a Bluetooth ID packetrecognition method thereof are desired to reduce power consumption ofthe communication apparatus when in a standby mode.

BRIEF SUMMARY OF THE INVENTION

A communication apparatus for recognizing an ID packet comprised in anRF signal and a method thereof are provided. An embodiment of acommunication apparatus is provided. The communication apparatuscomprises an RF module and a scan module coupled to the RF module. TheRF module receives an RF signal and generates an intermediary signalcorresponding to the RF signal. The scan module recognizes a time-domainpattern corresponding to the intermediary signal, and determines whetherthe RF signal comprises an ID packet according to the recognizedtime-domain pattern.

Furthermore, another embodiment of a communication apparatus isprovided. The communication apparatus comprises an RF module and a scanmodule. The RF module receives an RF signal. The scan module is coupledto the RF module and has at least two scan modes comprising a fast scanmode and a normal scan mode, wherein when operating in the fast scanmode, the scan module recognizes a time-domain pattern corresponding tothe RF signal and determines whether the RF signal comprises an IDpacket according to the recognized time-domain pattern.

Moreover, an embodiment of a method for recognizing an ID packetcomprised in an RF signal is provided. An RF signal is received and anintermediary signal corresponding to the RF signal is generated. A fastscan procedure is performed by recognizing a time-domain patterncorresponding to the intermediary signal, and determining whether the RFsignal comprises an ID packet according to the recognized time-domainpattern.

A detailed description is given in the following embodiments withreference to the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

The invention can be more fully understood by reading the subsequentdetailed description and examples with references made to theaccompanying drawings, wherein:

FIG. 1 shows a timing diagram illustrating page and inquiry scantransmissions;

FIG. 2A shows a communication apparatus for recognizing ID packetsaccording to an embodiment of the invention;

FIG. 2B shows a communication apparatus for recognizing ID packetsaccording to another embodiment of the invention;

FIG. 3 shows an example illustrating a timing diagram of the signals ofthe communication apparatus in FIG. 2A or FIG. 2B according to anembodiment of the invention;

FIG. 4 shows an example illustrating a diagram of the power detectionsignal S_(power) of the communication apparatus in FIG. 2A or FIG. 2Baccording to an embodiment of the invention;

FIG. 5 shows another example illustrating a diagram of the powerdetection signal S_(power) of the communication apparatus in FIG. 2A orFIG. 2B according to an embodiment of the invention;

FIG. 6 shows another example illustrating a diagram of the powerdetection signal S_(power) of the communication apparatus in FIG. 2A orFIG. 2B according to an embodiment of the invention;

FIG. 7 shows another example illustrating a diagram of the powerdetection signal S_(power) of the communication apparatus in FIG. 2A orFIG. 2B according to an embodiment of the invention; and

FIG. 8 shows an ID packet recognition method for a communicationapparatus according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The following description is of the best-contemplated mode of carryingout the invention. This description is made for the purpose ofillustrating the general principles of the invention and should not betaken in a limiting sense. The scope of the invention is best determinedby reference to the appended claims.

FIG. 2A shows a communication apparatus 200 for recognizing an ID packetaccording to an embodiment of the invention. The communication apparatus200 comprises an RF module 210, an analog to digital converter (ADC)220, and a scan module 230. In FIG. 2A, the RF module 210 receives an RFsignal via an antenna 260. Next, the ADC 220 receives a signal from theRF module 210 and converts the received signal into a digital signalS_(D). Next, the scan module 230 may perform a fast scan procedure onthe digital signal S_(D) to recognize a time-domain patterncorresponding to the digital signal S_(D) and to determine whether theRF signal received by the RF module 210 comprises an ID packet accordingto the recognized time-domain pattern. More specifically, the scanmodule 230 compares the recognized time-domain pattern with a predefinedID pattern, and determines that the RF signal comprises the ID packetwhen the comparison result indicates that the recognized time-domainpattern matches the predefined ID pattern. The time-domain pattern maycomprise a power distribution pattern. As shown in FIG. 2A, the scanmodule 230 comprises a power detection unit 240 and a packet recognitionunit 250. The power detection unit 240 periodically detects the power ofthe digital signal S_(D) to obtain a power detection signal S_(power).Next, the packet recognition unit 250 may determine whether the RFsignal comprises the ID packet according to a power distribution patternof the power detection signal S_(power) in time-domain and provides apower decision result S_(result) for subsequent processes. For example,after recognizing the Bluetooth ID packet from the RF signal, thecommunication apparatus 200 may detect that a peer Bluetooth devicewhich sent the Bluetooth ID packet is nearby, and then the communicationapparatus 200 may determine whether to set up a connection link with thenearby Bluetooth device according to the Bluetooth ID packet.

In one embodiment, the communication apparatus 200 may further comprisea down converter coupled between the RF module 210 and the scan module230 (as shown in FIG. 2B) for down converting the signal from the RFmodule 210 to generate an intermediary signal, such as an intermediatefrequency (IF) signal or a Baseband signal, and then the scan module 230may perform a fast scan procedure according to the intermediate signal,to recognize whether a Bluetooth ID packet is received. Furthermore, theADC 220 may be implemented between the power detection unit 240 and thepacket recognition unit 250 rather than prior to the power detectionunit 240, as shown in FIG. 2B, so as to reduce conversion distortioncaused by the ADC 220 and obtain the power detection signal S_(power)accurately. In other words, the power detection can be implemented ineither analog or digital domain, and in either RF bands, IF bands orbasebands.

FIG. 3 shows an example illustrating a timing diagram of the signals ofthe communication apparatus 200 in FIG. 2A or FIG. 2B according to anembodiment of the invention. In FIG. 3, signal S1 represents a BluetoothID packet format (in this embodiment, eight slots ST1-ST8 are shown asexample), and signal S2 represents a power waveform of the signal S1received by the RF module 210 of FIG. 2A or FIG. 2B. Taking FIG. 2A asan example, the power detection unit 240 may obtain the power detectionsignal S_(power) by sampling the digital signal S_(D) and comparing thesample values with a threshold value. Therefore, the power detectionsignal S_(power) is at a high logic level “1” when the signal S2 hasexceeded the threshold value, and the power detection signal S_(power)is at a low logic level “0” when the signal S2 has not exceeded thethreshold value. If the ID packet exists, at least two power peaks (forexample, the peaks in slot ST1 and ST2, or the peaks in slot ST2 andslot ST5) of the digital signal S_(D) will be detected by the powerdetection unit 240 over 1005.5 μs. Thus, the power detection unit 240may provide the power detection signal S_(power) comprising N-bit powerdistribution patterns covering at least 1005.5 μs to express the powerdistribution of the digital signal S_(D). Although N-bit hard decisionis described here as an example, it should be noted that soft powerinformation can also be employed to detect the two power peaks.

FIG. 4 shows an example illustrating a diagram of the power detectionsignal S_(power) of the communication apparatus 200 in FIG. 2A or FIG.2B according to an embodiment of the invention. In the embodiment, eachtime period T1 includes N sub-periods (e.g. 18 sub-periods, eachsubstantially equal to 72 μs) and each of the N bits indicates the powerlevel during a corresponding sub-period within T1. It is to be notedthat the time-length of the time period T1 must be large enough to cover1005.5 μs, so as to contain at least two power peaks of the digitalsignal S_(D), as described above. In FIG. 4, the power distributionpattern is composed of 18 bits. Two different power distributionpatterns P1 and P2 are shown in FIG. 4. After receiving the powerdetection signal S_(power), the packet recognition unit 250 determineswhether the power distribution pattern P1 or P2 matches a predefinedBluetooth ID pattern. If the power distribution pattern matches apredefined Bluetooth ID pattern, the packet recognition unit 250determines that a Bluetooth ID packet is detected. As can be seen fromFIG. 3, ID packets can be expressed as two bits with high logic level“1” separated by a time interval close to 312.5 μs or 937.5 μs. In thepower distribution pattern P1, label 41 constituted by two bits with ahigh logic level “1” separated by 2 bits with a low logic level “0” isclose to 312.5 μs. In the power distribution pattern P2, label 42constituted by two bits with a high logic level “1” separated by 10 bitswith a low logic level “0” is close to 937.5 μs. Therefore, the powerdistribution patterns P1 and P2 match one type of Bluetooth ID pattern,respectively.

FIG. 5 shows another example illustrating a diagram of the powerdetection signal S_(power) of the communication apparatus 200 in FIG. 2Aor 2B according to an embodiment of the invention. Similarly, in FIG. 5,the power distribution pattern is obtained by detecting the power of thedigital signal S_(D) every 72 μs for 18 times. Furthermore, twodifferent power distribution patterns P3 and P4 are shown in FIG. 5.After receiving the power detection signal S_(power), the packetrecognition unit 250 of FIG. 2A or 2B may provide the power decisionresult S_(result) to indicate that whether the power distributionpattern P3 or P4 matches a Bluetooth ID pattern. For example, in thepower distribution pattern P3, no two bits with a high logic level “1”are separated by 312.5 μs or 937.5 μs, and the number of continuous bitswith a high logic level “1” is larger than or equal to a specific value(e.g. ≧4), as shown in label 51; thus the packet recognition unit 250may determine that the power distribution pattern P3 does not match anyBluetooth ID pattern and is a noise/interference pattern. In addition,in the power distribution pattern P4, although two bits with a highlogic level “1” separated by 2 bits with a low logic level “0” aredetected (label 52 and label 53), the packet recognition unit 250 stilldetermines that the power distribution pattern P4 does not match aBluetooth ID packet because there are four continuous separation groupseach composed of a bit with a high logic level “1” and one or more bitswith a low logic level “0” subsequent to the bit with a high logic level“1”, as shown in labels 54, 55, 56 and 57 of FIG. 5. Due to the numberof continuous separation groups of the power distribution pattern P4being larger than or equal to a specific value (e.g. ≧4), the packetrecognition unit 250 may determine that the power distribution patternP4 matches a noise/interference pattern rather than a Bluetooth IDpattern and provide the power decision result S_(result) to notifysubsequent circuits, wherein the specific value is determined accordingto implementation choice.

FIG. 6 shows another example illustrating a diagram of the powerdetection signal S_(power) of the communication apparatus 200 in FIG. 2Aor 2B according to an embodiment of the invention. Similarly, in FIG. 6,each power distribution patterns P5-P8 is obtained by detecting thepower of the digital signal S_(D) every 72 μs for 18 times. In thisembodiment, each of the power distribution patterns P5, P6, P7 and P8has no bit with a high logic level “1”, which means that the power ofthe digital signal S_(D) has not exceeded the threshold value duringfour continuous fast scan procedures. In this situation where thetime-domain patterns indicate that no power or low power level has beendetected for a given time period, the scan module 230 may switch fromthe fast scan mode to the normal scan mode, and the normal scanprocedure may be performed during a scan window (11.25 ms) to furtherconfirm whether the RF signal received by the antenna 260 comprises anyBluetooth packets or noise.

FIG. 7 shows another example illustrating a diagram of the powerdetection signal S_(power) of the communication apparatus 200 in FIG. 2Aor 2B according to an embodiment of the invention. Similarly, the powerdistribution pattern P9 is obtained by detecting the power of thedigital signal S_(D) every 72 μs for 18 times. In this embodiment, thenumber of continuous bits with a high logic level “1” of the powerdistribution pattern P9 is larger than or equal to a specific value(e.g. 16). Thus, the packet recognition unit 250 may determine that thepower distribution pattern P9 does not match a Bluetooth ID pattern andprovide the power decision result S_(result) to notify subsequentcircuits. In this situation where the time-domain pattern indicates thathigh power level or interference has been detected for a given timeperiod, the scan module 230 may switch from the fast scan mode to thenormal scan mode to further confirm whether the RF signal received bythe antenna 260 comprises any Bluetooth packets or noise such asinterference caused by a Wi-Fi packet.

FIG. 8 shows an ID packet recognition method for a communicationapparatus according to an embodiment of the invention. First, an RFsignal is received via an antenna (e.g. 260) and an RF module (e.g. 210)of the communication apparatus (step S802). Next, in step S804, the RFsignal is converted into an intermediary signal, e.g. a digital signal,an intermediate frequency signal or a Baseband signal. Next, in stepS806, a fast scan procedure is performed by a scan module (e.g. 230) ofthe communication apparatus on the intermediary signal to obtain a powerdistribution pattern corresponding to the intermediary signal in a timedomain, and to obtain a power decision result corresponding to the RFsignal according to the power distribution pattern. Next, in step S808,a subsequent process is performed according to the power decision resultobtained in step S806. For example, if the power decision resultindicates that the power distribution pattern matches a Bluetooth IDpattern (e.g. P1 or P2 of FIG. 4), the communication apparatus mayestablish a link with the peer Bluetooth device based on the ID packet.If the power decision result indicates that the power distributionpattern matches a noise/interference ID pattern (e.g. P3 or P4 of FIG.5), the communication apparatus may determine that the RF signal hasnoise interference or the RF signal does not comprise any Bluetooth IDpackets. Thus, the communication apparatus may continue performing thefast scan procedure periodically to monitor the power distributionpattern corresponding to the intermediary signal in a time domain. Ifthe power decision result indicates that no power or low power has beendetected in the power distribution pattern for a given time period (e.g.P5-P8 of FIG. 6), the communication apparatus may stop performing thefast scan procedure and then start to perform a normal scan procedure tofurther confirm whether the RF signal comprises any Bluetooth IDpackets. If the power decision result indicates that high power levelhas been detected in the power distribution pattern (e.g. P9 of FIG. 7),the communication apparatus may stop performing the fast scan procedureand then start to perform a normal scan procedure to further confirmwhether the RF signal comprises a plurality of Bluetooth ID packets orhas noise interference caused by a Wi-Fi packet. Therefore, byperforming the fast scan procedure of the invention, a communicationapparatus can determine whether an ID packet exists faster; thusreducing power consumption. Furthermore, high detection rate and lowfalse alarm rate are obtained for page and inquiry scans in a Bluetoothcompatible network.

While the invention has been described by way of example and in terms ofthe preferred embodiments, it is to be understood that the invention isnot limited to the disclosed embodiments. To the contrary, it isintended to cover various modifications and similar arrangements (aswould be apparent to those skilled in the art). Therefore, the scope ofthe appended claims should be accorded the broadest interpretation so asto encompass all such modifications and similar arrangements.

1. A communication apparatus, comprising: an RF module, for receiving anRF signal and generating an intermediary signal corresponding to the RFsignal; and a scan module, coupled to the RF module, for recognizing atime-domain pattern corresponding to the intermediary signal, anddetermining whether the RF signal comprises an ID packet according tothe recognized time-domain pattern.
 2. The communication apparatus asclaimed in claim 1, wherein the scan module compares the recognizedtime-domain pattern with a predefined ID pattern, and determines thatthe RF signal comprises the ID packet when the comparison resultindicates that the recognized time-domain pattern matches the predefinedID pattern.
 3. The communication apparatus as claimed in claim 1,wherein the time-domain pattern comprises a power distribution patternof the intermediary signal, and the scan module comprises: a powerdetection unit, coupled to the RF module, for detecting power level ofthe intermediary signal during a specific time period to generate thepower distribution pattern of the intermediary signal; and a packetrecognition unit, coupled to the power detection unit, for determiningwhether the RF signal comprises the ID packet according to the powerdistribution pattern.
 4. The communication apparatus as claimed in claim3, wherein the power distribution pattern comprises N bits, the specifictime period comprises N sub-periods, and each of the N bits indicatesthe power level of the intermediary signal during a correspondingsub-period within the specific time period.
 5. The communicationapparatus as claimed in claim 4, wherein each bit with a first logiclevel is used to indicate that the power level of the intermediarysignal during the corresponding sub-period has exceeded a thresholdvalue, and each bit with a second logic level different to the firstlogic level is used to indicate that the power level of the intermediarysignal during the corresponding sub-period has not exceeded thethreshold value.
 6. The communication apparatus as claimed in claim 5,wherein the power distribution pattern matches a predefined Bluetooth IDpattern when two bits with the first logic level of the powerdistribution pattern are separated by a time interval close to 312.5 μsor 937.5 μs.
 7. The communication apparatus as claimed in claim 5,wherein the power distribution pattern does not match a predefinedBluetooth ID pattern when the number of continuous bits with the firstlogic level of the power distribution pattern is larger than or equal toa specific value.
 8. The communication apparatus as claimed in claim 5,wherein the power distribution pattern does not match a predefinedBluetooth ID pattern when the number of continuous separation groups ofthe power distribution pattern is larger than or equal to a specificvalue, wherein each of the separation groups is composed of a first bitwith the first logic level and one or more second bits with the secondlogic level which is/are subsequent to the first bit.
 9. Thecommunication apparatus as claimed in claim 3, further comprising: ananalog-to-digital converter, coupled between the power detection unitand the packet recognition unit, for sampling the power distributionpattern of the intermediary signal to generate a plurality of samplingresults; wherein the packet recognition unit determines whether the RFsignal comprises the ID packet according to the plurality of samplingresults.
 10. The communication apparatus as claimed in claim 1, furthercomprising: an analog-to-digital converter, coupled between the RFmodule and the scan module, for sampling the intermediary signal togenerate a plurality of sampling results; wherein the scan modulerecognizes the time-domain pattern corresponding to the intermediarysignal based on the plurality of sampling results.
 11. The communicationapparatus as claimed in claim 1, implemented to recognize a Bluetooth IDpacket, and when the scan module determines that the RF signal comprisesan ID packet sent by a peer Bluetooth apparatus, the communicationapparatus is configured to establish a link with the peer Bluetoothapparatus based on the ID packet.
 12. A communication apparatus,comprising: an RF module, for receiving an RF signal; and a scan module,coupled to the RF module and having at least two scan modes comprising afast scan mode and a normal scan mode, wherein when operating in thefast scan mode, the scan module recognizes a time-domain patterncorresponding to the RF signal and determines whether the RF signalcomprises an ID packet according to the recognized time-domain pattern.13. The communication apparatus as claimed in claim 12, wherein the scanmodule compares the recognized time-domain pattern with a predefined IDpattern, and determines that the RF signal comprises the ID packet whenthe comparison result indicates that the recognized time-domain patternmatches the predefined ID pattern.
 14. The communication apparatus asclaimed in claim 12, wherein the scan module switches from the fast scanmode to the normal scan mode when the time-domain pattern correspondingto the RF signal indicates that no power or low power level has beendetected for a given time period.
 15. The communication apparatus asclaimed in claim 12, wherein the scan module switches from the fast scanmode to the normal scan mode when the time-domain pattern correspondingto the RF signal indicates that high power level or interference hasbeen detected for a given time period.
 16. A method for recognizing anID packet comprised in an RF signal, comprising: receiving an RF signaland generating an intermediary signal corresponding to the RF signal;and performing a fast scan procedure, comprising: recognizing atime-domain pattern corresponding to the intermediary signal; anddetermining whether the RF signal comprises an ID packet according tothe recognized time-domain pattern.
 17. The method as claimed in claim16, wherein the determining step comprises: comparing the recognizedtime-domain pattern with a predefined ID pattern; and determining thatthe RF signal comprises the ID packet when the comparison resultindicates that the recognized time-domain pattern matches the predefinedID pattern.
 18. The method as claimed in claim 16, wherein thetime-domain pattern comprises a power distribution pattern of theintermediary signal, the step of recognizing the time-domain patterncorresponding to the intermediary signal comprises: detecting the powerlevel of the intermediary signal during a specific time period togenerate the power distribution pattern of the intermediary signal; andthe step of determining whether the RF signal comprises the ID packetcomprises: determining whether the RF signal comprises the ID packetaccording to the power distribution pattern.
 19. The method as claimedin claim 18, wherein the power distribution pattern comprises N bits,the specific time period comprises N sub-periods, and each of the N bitsindicates the power level of the intermediary signal during acorresponding sub-period within the specific time period.
 20. The methodas claimed in claim 16, further comprising: performing a normal scanprocedure when the recognized time-domain pattern corresponding to theintermediary signal indicates that no power or low power level has beendetected for a given time period.
 21. The method as claimed in claim 16,further comprising: performing a normal scan procedure when therecognized time-domain pattern corresponding to the intermediary signalindicates that high power level or interference has been detected for agiven time period.